RT Journal Article SR Electronic(1) A1 Guerrero-Barrera, Alma L. A1 de la Garza, Mireya A1 Mondragón, Ricardo A1 Garcı́a-Cuéllar, Claudia A1 Segura-Nieto, Magdalena YR 1999 T1 Actin-related proteins in Actinobacillus pleuropneumoniae and their interactions with actin-binding proteins JF Microbiology, VO 145 IS 11 SP 3235 OP 3244 DO https://doi.org/10.1099/00221287-145-11-3235 PB Microbiology Society, SN 1465-2080, AB A group of prokaryotic actin-related proteins (PARP) with an M r of 43000 was detected in Actinobacillus pleuropneumoniae. These proteins were enriched by a depolymerization/polymerization cycle, under similar conditions to those used to polymerize muscle actin, and purified by affinity chromatography on a DNase I-Sepharose column. Three isoforms of A. pleuropneumoniae PARP (Ap-PARP) with pI values of 5·8, 6·15 and 6·2 were detected. Ap-PARP were recognized by four different anti-actin antibodies (one anti-muscle and three anti-cytoplasmic isoforms). Ap-PARP were also recognized by antibodies against Anabaena variabilis PARP (Av-PARP) and against actin-binding proteins such as α-actinin and spectrin, and also by a monoclonal antibody against heat-shock cognate protein 70 (Hsc70). Specific binding of phalloidin to Ap-PARP was detected both in permeabilized cells and in vitro. Purified Ap-PARP can polymerize under similar conditions to those required for skeletal muscle actin polymerization and the filaments formed appear to be decorated with myosin subfragment-1 (S1) as observed by transmission electron microscopy. The amino acid composition of Ap-PARP revealed more similarities to muscle γ-actin and the cytoplasmic β-actin isoform than to eukaryotic actin-related proteins., UL https://www.microbiologyresearch.org/content/journal/micro/10.1099/00221287-145-11-3235